Lightning-arrester.



H. C. WIRT.

LIGHTNING ARRESTER.

APPLIUATION FILED DB0.22,1905.

958,454. Patented May 17, 1910.

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WTNESSES- INVENTD F1- @y HERbERTEM/IRT.

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Hummm. l y p 953,454,` specification ef team nant. pratenfeid May 17,l19,10,

g museum sued neemneras, swarm. $92,927. i To all whomitmdy concern: lthe tiret gap, thereby de?) roying its electro- -Be itknownthatl, Hnnm'rC. Wm'r, a citizen of the United. States, 'residin at Schenectady,county of Schenectady, .tate of New York, have mvented oertainnew anduseful Improvements in .Lightning-Arresters, of `which the following isaspecification.

My invention relates todevices for protecting electrical circuits .andapparatus from static and high voltage strains resulting from lightningor other causas` In the design of a successful lightning arrester twoimportant requirements must be satisfied, first, the device -mustpresent a ready path' to ground for static or lother abnorma charges,and second, it must not permit Athe line current to follow through toground on the arc established by the high potential discharge. lTheapparatus which I have devised for carrying out these two requirementsincludes a plurality of conducting -members grouped u on an insulatingbase lto form a plura ty of -spark gaps, and the conductors and gaps areyso proportioned and are in such number that the arrester unit as .awhole maybe connected directly lbetween the line to beprotected and asecond conductor, such as ground, without the interposition ofv anyseries-resistance or other impedance devices which -might, under certaincircumstances, cause a choking of high potentialdischarges, especially'when these ,discharges are of the exceedingly high frequency sometimesen.- countered in lightning arrester work.

When using` a plurality of spark gaps without resistance in series, as.abovedescribed, I find it desirable to utilize the electrostaticcapacity of the conductors which form the conducting poles of theseveral Vspark gaps. .B this arrangement the spark gaps are bro en downsuccessively, and not simultaneously as would, no doubt, be necessary ifthe electro-static capacity of the conductors w'as not utilized.Thissuccessive breaki gaps was, II believe, first disclosed in a patentto Elihu Thomson, 444,687 of Jan. 13, 1891. The successive reaking downof the several gaps-is, in my opinion, due to Y the-fact .that thestaticcharge readily jumps down of the several spark t static resistance, anjectmg the second gap to substantially the full force of the staticcharge, whereupon the second gap is likewise broken down and permits thecharge to pass-on to alli-the gaps isu succession. When this principleis applied to alternatingcurrent circuits the electro-static capacity ofthe several conducting elementsv of the arrester gives to the dischargepaths. certain selective action whereby discharges of a certainfrequency-are' ermitted to pass, although the path is su tantiallyimpervious to vdischarges of a'lower frequency. This selective orresonant action ofthe discharge path is of prime importance inpreventing the line current from following through on the static Idischarge.

My invention embodies novel vfeatures of construction andarrangement andin order that my invention may be better understood, reference will behad to the following description taken in connection with the drawingforming a part of this specification.

Figure 1 is a perspective view of my improved lightning arrester unit;Fig, 2 shows three of these units arranged one above another to form azigzag path for the discharge current; .and Fig. 3 is a side elevationshowlng details of construction.

` The uni-t shownin Fig. 1 comprises a porcelain or other insulatingbase l, and .a pluralityofmetal cylinders :2 arranged in the form of aV. These cylinders are mounted on suitable pins cemented or otherwiseset into the porcelain base and are locked inpcsition by the nuts 4. VIhave found that' the diameter and length of these metal cylinders havean important bearing-on their electrostatic capacity, and consequentlyon the resistance to break down oiiered by the spark gaps whichintervene between one cylinder and another. I find that the size andshape say of 1/32, for when so constructed and arranged theelectro-static capacity 1s very satisfactory for commercial operation.

By arranging the cylinders as shown in Fi 1 an arc or discharge enteringon one sidi of the cylinder is transmitted across the cylinder andleaves at a diainetrically opposite point, and even before the arc ordischarge forms there is more or less of a concentration ofelectro-static energy on those portions of the conducting cylinderswhich are nearest to adjacent cylinders, it being understood that theelectro-static strain or charge is confined principally to the outersurface of each conducting cylinder.

The number of gaps to be used, in each particular installation dependson the voli tage of the circuit, but for a 33,000 volt circult operatingat a usual frequency, I find that 624 gaps between lines will break downunder abnormal static strain and will satisfactoril break the dynamicarc established by the ine current.

In commercial installations the most destructive effects are produced byhigh frequency discharges, and the multi-gap arrangement abovedescribed, Without series resistance of any kind, is especially suitedto readily transmit these discharges. At the same time the arresterforms an adequate rotection against high voltages having a equency offive hundred to one thousand cycles, which might be generated in theline by resonance or other disturbing phenomena more 'or lessindependent of atmospheric disturbances.

The V shaped arrangement shown in Fig. 1, affords several importantadvanta es; first, it properly separates the rst and ast cylinders 5 and6 of each unit so that there is no danger of the discharge jumpingacross between these conductors in preference to passing across theseries of gaps, and second, it places each gap in such a position thatthe discharge or are which forms is substantially horizontal, and henceis acted upon by a draft of hot air tending to bow it up in the center,thereby increasing its length and forcing it upward over the curvedsurfaces of adjacent cylinders. As the increase in are length producedby the draft occurs at each spark gap the total increases in arcingdistance is very great, and consequently is very effective in producingthe' extinction of the are. The V-shaped arrangement also makes itpossible to conveniently group the unitsy one above another without theintervention of complicated Wiring or other parts Which would be hard toinsulate at the high potentials commonly present in lightning arresters.

I contemplate connecting a group of units as shown in Fig. 2, direct yacross between line conductorsy 7 and 8, though it is to be understoodthat the total number of units thus connected is calculated for eachparticular installation, and is dependent on the workingvolta el of theline and on other factors of a li ce' nature. For high voltage systems-I may use as many as twenty-ve units arranged in the same manner as thethree units of Fig. 2. Instead of connecting the spark ga s between lineconductors I may if desire connect a group between each line conductorand ground, thus securing separate paths to ground for each lineconductor and atl the same time securing a ath between any twoconductors by way o the two corresponding groups, in series.

. As previously stated the electro-static capacity of the cylinders isbelieved to produce the break down at each gap, these break downsoccurring one after another and thereby transmitting to successive gapssubstantially lall the electro-static strain to which the first gap wassubjected. The total spark gap distance traversed by the high potentialdischarge is thus made very much greater than the distance which itwould jump between two fixed needle points, or in other Words thisseries of gaps has a very low equivalent spark gap. Not only does myimproved arrester provide for a rapid removal of high potential, highfrequency charges, but it 1s also'exceedingly effective in suppressingthe following line current, and furthermore, suppresses this currentalmostl at the instant it is formed, thereby preventing sudden currentrushes on the system, which if allowed to form might produceoscillations, resonance and other phenomena highly detrimental to rotaryconverters or other sensitive apparatus operating on the system. l

What I claim as new and desire to secure Vby Letters Patent of theUnited States, is:

1. In a lightning arrester, the combination of an insulating base, and aplurality of conducting cylinders supported on said base and grouped intwo converging rows.

2. In a lightning arrester, the combination of a plurality of units eachcomprising an insulating base and a lurality of conductin membersmounted t ereon, said units being isposed in proximity to each other toform a discharge path for high potential charges, and the end members ofadjacent units being separated by-air gaps.

3. The combination with the conductors of an electrical distributioncircuit, of a plurality of conducting members spaced apart to form airgaps and grouped to form a zigzag path for high potential dischargesfrom I one of said conductors.

4. In a lightning arrester, the combination of an insulating base and aplurality of conducting cylinders supported thereon, said converging butapproximately horizontal l0 cylinders being arranged in two approxilines und with their axes substantially horimutely horizontal converginglines to permit. i zontal. u rapid circulation of air between said eyl-In Witness whereof I have hereunto set my iuders when an arc formstherebetween. hand this 20th day of December, 1905.

5. In a lightning arrester, the combination HERBERT C. WIRT. of aninsulating base, and a plurality of conducting cylinders supportedthereon, said cylinders being arranged in a plurality of Witnesses:

BENJAMIN B. HULL, HELEN ORFoRD.

